Associations between the brain age gap (BAG), sociobehavioural factors, and cognitive functions in a cross-sectional lifespan study

Sociobehavioural factors (e.g., educational attainment, occupational complexity, etc.) are important for maintaining optimal cognitive functioning in aging. For example, higher levels of educational attainment and occupational complexity have been linked to higher levels of cognitive performance in older age, despite the presence of age-related changes in brain integrity. However, the underlying mechanisms through which they exert their effect remain unclear. To investigate which of these underlying mechanisms best explain the associations between BAG, sociobehavioural factors, and cognitive performance we compare several models: 1) Sociobehavioural factors moderate the effects of brain health on cognitive functions; 2) effects of sociobehavioural factors on cognitive functions are mediated by brain health; 3) sociobehavioural factors and brain health are independently associated with cognitive functions. Furthermore, we expect that, overall, sociobehavioural factors (i.e., educational attainment, leisure activities, occupational complexity) exert positive effects on cognitive functioning. Lastly, to obtain a more complete picture of these associations across the adult lifespan, we investigate whether each model (i.e., moderation, mediation, independent effects) differs between age groups (18-39, 40-64, 65-79 years old).